At present, the mode of igniting an exothermic welding flux with an ignition agent is usually applied to the ignition of exothermic welding flux, while the high instability of ignition agent leads to reduction of safety factor. Moreover, the mode of igniting an exothermic welding flux with an ignition agent leads to increased cost, which adversely affects the industrial manufacture. In terms of the current technology in the art, it is difficult to achieve a continuous and stable high temperature to ignite an exothermic welding flux, thus the mode of ignition agent have to be used until the present.
The present inventors found from his researches that there are at least the following disadvantages in conventional exothermic welding processes:
low safety factor of construction operation,
complex operation, and
high cost.